<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS</title>
    <style>
        .a {
            color: red;
        }

        .b {
            font-size: 26px;
        }
    </style>
</head>

<body>
    <p>段落1</p>
    <!-- 多个class选择器，使用空格隔开 -->
    <p class="a b">段落2</p>
    <p>段落3</p>
    <p class="a">段落4</p>
    <p>段落5</p>
    <p>段落6</p>
</body>

</html>